Centrifugally armed and self-destroying impact fuze



Feb. 9, 1960 A. G. NEUWIRTH, JR., ETAL CENTRIFUGALLY ARMED ANDSELF-DESTROYING IMPACT FUZ'E Filed Sept. 21, 1955 2 Sheets-Sheet 1INVENTORS Alnia E-NEL1WiI t1L Ur:

Furka H. Thompson BY i i): fl w- ATTOR NE Y5 Feb. 9, 1960 A. G.NEUWIRTH, JR, ET AL ,1

CENTRIFUGALLY ARMED AND SELF-DESTROYING IMPACT FUZ E Filed Sept. 21,1955 2 Sheets-Sheet 2 lNl/ENTO Alui s G. Nauwirth,

FurKe H- Thompson 7 BY ZzM+ if).

' ATTORNEYS United States Patent CENTRIFUGALLY ARMED AND SELF-DESTROY-ING IMPACT F UZE Alois G. Neuwirth, In, St. Louis County, and Parke H.Thompson, Kirkwood, Mo., assignors to the United States of America asrepresented by the Secretary of the Army Application September 21, 1955,Serial No. 535,773

Claims. (Cl. 102-71) This invention relates to fuzes for spin typeprojectiles.

An object of the invention is to provide a fuze which is positively heldin unarmed position until it develops sutficient spin in flight to moveweighted detents, under the influence of centrifugal force, to aposition whereby a firing pin is caused to move from unarmed to armedposition by movement of the detents.

Another object of the invention is .to provide a fuze having a nose capof frangible material insuring rapid detonation thereof on impact with.a target constructed of easily penetrated materials.

A further object of the invention is to provide a fuze which willdetonate on decay of spin if the projectile penetrates a target withoutdetonation on impact therewith.

Other objects and advantages will be apparent from the followingdetailed description and the accompanying drawings, in which:

Fig. 1 is a longitudinal sectional view of a fuze disclosing one form ofthe invention,

Fig. 2 is a transverse sectionalview taken on the line 2-2 of Fig. 1 andlooking in the direction of the arrows,

Fig. 3 is a longitudinal sectionalview of the nose cap insert shown inFig. 1,

Fig. 4 is a detail perspective of one of the detents shown in Fig. 1,

Fig. 5 is a longitudinal sectional view of a modified form of theinvention, 7

Fig. 6 is a similar view taken on the line 6--6 of Fig. 5 and looking inthe direction of the arrows,

Fig. 7 is a fragmentary longitudinal sectional view of a furthermodified form of the invention, and

Fig. 8 is a similar view taken on the line 88 of Fig. 7 and looking inthe direction of the arrows.

Referring now to Figs. 1 through 4 of the'drawings. The fuze is formedwith a body portion 1 rotatable about a longitudinal axis and carrying abooster charge 2. The body portion has an internal cavity 3-in which agenerally spherical rotor 4 is movable from a safe to an armed positionunder the influence of centrifugal force. The rotor has a primer charge5 'fixed within a diametral bore therein and a recess 6 formed in itssurface as will be clear from Fig. l. A firing pin 7 is slidable incoaxial alignment with the axis of the fuze body and engages in therecess 6 to maintain the fuze unarmed by holding the primer charge 5 outof alignment with the firing pin 7 and booster charge 2. In its forwardface the body portion 1 is formed with a bore 8 in which is seated thediametrically reduced end 9, of an insert 10, for limiting the rotor 4to rotation only in the cavity 3. For this purpose it will be noted thatbody 1 and insert 10 have cooperating recesses 1a and 10a, respectively,fitting smoothly about the corresponding surfaces of the rotor. A nosecap 11 of thin material envelops the insert 10 and the forward part ofthe fuze body 1 and is secured thereto as at 12 by any-suitable-meanssuch as rdlling. The insert is formed with anaxi'al bore 13 and a.coaxial counterbore 14 providing a shoulder 15 at their "Ice juncture. Ahead 16 is secured on the forward end of the firing pin 7 and slides inthe bore 13 to guide the forward end of the firing pin in axialtranslation. An annular enlargement 17 forming a shoulder is formed onthe firing pin near its rear end. A generally, hollow, frusto-conicalfirst spring housing 18 surrounds the firing pin 7 and has formedthereon a base flange 19 seated against the shoulder 15. As clearlyshown upon Fig. 1,

this housing extends real-wardly into counterbore 14. A.

first spring 20, within the first spring housing 18 and surrounding thefiring pin 7, is confined between the closed end of the housing 18 andthe firing pin head 16 for normally urging the firing pin forwardly.Surrounding the first spring housing 18 and slidable in the counter bore14 is a second spring housing 21 shown as gener ally cylindrical'in formand enclosing a second spring. 22. The second spring housing isdiametrically reduced at its rear end as at 23, to engage the annularenlarge-- ment 17 onthe firing pin 7 and houses the second spring: 22bearing at its forward and rearward ends upon flange- 19 and reduced end23 of the second housing, respec-- tively. The second spring 22 is ofgreater strength than:

spring 20 so that the parts are normally maintained its the positionshown upon Fig. 1, with the tip of firing pin 7 seated in recess 6 ofrotor 4. It will be noted that the enlargement 17 on the rear end of thefiring pin, in conjunction with the reduced end and neck portion ofhousing 21, define an annular recess.

The insert 10 is formed with longitudinal slots 25 shown as four innumber and uniformly spaced around the circumference thereof, Figs. 2and 3. A detent 26 is positioned in each slot and is dimensioned to havea smooth fit therein. The detents are alike and shaped as clearly shownin Fig. 4, to provide finger 27 which contacts with an abutment 24 onthe second spring housing 21. Each detent is confined for movementwithin its respective slot 25 by the side wall of the nose cap 11invention all four detents constantly engage the abut ment 24.

The operation of the device shown in Figs. 1 through:

4 is as follows:

When a projectile, to which the fuze is attached, ro-- tates in flightthe detents 26 move outwardly in response tocentrifugal force. Themasscenter of each detent is well forward of its pivot point 28.Consequently each; detent will move "powerfully outwardly to the dottedline position, Fig. 1. During this movement the fingers 27 bear againstthe annular abutment 24 and move the second spring housing 21 forwardlycompressing the second spring 22 and freeing the firing pin 7 forforward movement under the bias of the first spring 20 to armedposition. When the rear end of the firing pin is withdrawn from therecess 6 in the rotor 4, the rotor precesses in response to spin of theprojectile until the primer 5 is coaxially aligned with the firing pinin fully armed position. If a hit is made on a target the forward end ofthe nose cap 11 and insert 10 will be deformed and the firing pin willbe forced into the primer 5. In the event that the target is too frailto deform the nose cap and insert, and the projectile continues beyondthe target, eventual decay of spin will correspondingly lessen forwardthrust of the detent fingers 27. In such an event the spring 22 willovercome the lessened thrust of the detent fingers and the bias ofspring 20, and will drive the second sleeve 21 and its reduced end 23against the shoulder formed by the enlargement 17 on the, firing pin anddetonate the primer charge 5.

In the modified form of the invention shown in Figs.

and 6 a single spring element is employed instead of the two springassembly of Fig. l.

A body portion 1' carries a booster charge 2 and a rotor 4 having aprimer charge 5 therein normally out of registry with a firing pin 7. Arecess 6 is formed in the rotor 4 and in normal safe position is incoaxial engagement with the firing pin. Secured to the forward end ofthe fuze body, by any preferred means, is a nose cap 11 of thinmaterial. An insert which may be made of frangible material, is fittedwithin the nose cap and formed with an axial bore 13'. Positioned in theforward end of bore 13 of the insert 10 is a cylindrical guide member 32having an annular spring seat 33 formed thereon. The firing pin 7 has adiametrically enlarged portion 17' at its rear end forming a shoulder.

An elongated sleeve 34 is slidably supported at its forward end in thecylindrical guide 32 and the firing pin 7 is guided for axial sliding inand by sleeve 34. At its rear end the sleeve 34 is formed with anoutturned flange 34a which serves as an abutment for the detents 36 andalso for the spring, through the intermediary of an annular reinforcingcollar 35, slidably fitting the bore 13. A spring 22 surrounds thesleeve 34 and is confined between the spring seat 33 on the guide 32 andthe abutment reinforcing collar 35. In normal safe position the bias ofspring 22' directed against the collar 35 and the outturned flange 34aholds the firing pin seated in the recess 6 in the rotor 4.

The insert 10' is formed with longitudinal slots 25" diametricallyopposite each other as shown in Fig. 5, and slots 25' diametricallyopposite each other and located at an angle of 90 from the slots 25" asshown in Fig. 6. These slots totaling four in number correspond inlocation, form, and purpose with slots 25 in insert 10 of the form shownat Fig. 3.

Two pairs of detents 26 and 36 of slightly different form and functionare employed. The detents 26, Fig. 6, have fingers 27' in contact withthe outturned flange 34a on the sleeve 34. Diametrically oppositedetents 26 are identical and are confined in respective slots 25' in theinsert 10', in the same manner as the detents of Fig. l. The two detents26', Fig. 6, are each formed with a pointed end 28 which forms a fulcrumand engages a stop member 37 in each slot 25 and pivots thereon underthe influence of spin to retract and hold the sleeve 34 and itsoutturned flange 34a in armed position against the thrust of spring 22'.The two detents 36, Fig. 5, have pointed ends 28 which pivot on thefront face 29 of the body portion similar to the detents 26 of Fig. 1but the fingers 27" of these detents, that is, the fingers whichprotrude radially behind flange 34a are formed of lesser longitudinaldimension so that when the detents 26' have reached their extremeoutward position in flight as shown in dotted lines upon Fig. 6, and areholding the sleeve 34 retracted, the detents 36 will have movedoutwardly to the dotted line position shown in Fig. 5, in which positionthey are free of the outturned flange 34a on the sleeve 34. The fusethus becomes more sensitive to impact when held in firing position byonly one pair of detents, namely, detents 26'.

The operation of the device shown in Figs. 5 and 6 is as follows:

When a projectile, to which the fuze is attached, rotates in flight thedetents 26 and 36 move outwardly in response to centrifugal force in thesame manner as the detents of Fig. 1. During this movement the fingers27 of detents 26' and the fingers 27" of detents 36 bear against theoutturned flange 34a and move the sleeve 34 forwardly compressing thespring 22' and freeing the firing pin to float in the sleeve 34 andcreep forward during flight thus freeing rotor 4 for precession to armedposition. When the sleeve and spring are retracted to armed position andthe detents 26' are in the broken "line position of Fig. 6. the detents36 are released and 4 moved to the broken line position of'Fig, 5 .sothat the fuze is held in armed position by the detents 26 only.

A further simplified form of the invention is shown in Figs. 7 and 8. Abody portion 1 carries a rotor 4 having a primer charge 5 thereinnormally out of registry with a firing pin 7a. A recess 6 is formed inthe rotor and in normal safe position is in coaxial engagement with thefiring pin. Secured to the forward end of the fuze body, by anypreferred means, is a nose cap 11 of thin material. An insert 10a, whichmay be made of frangible material is fitted within the nose cap andformed with an axial bore 13a and a counterbore 14a. The firing pin 7ahas an enlarged head 16a slidable in .the bore 13a and annular grooves40 near its rear end. All annular separable member 41 surrounds thefiringpin and is engaged in the grooves 49. The separable member slidesin the counterbore 14a and serves as an abutment 24a similar to theabutment of Figs. 5 and 6. At the juncture of the bore 13a and thecounterbore 14a a shoulder 15a is formed between which and the separablemember 41 a spring 22a is confined. centrifugally operated detents 36aare movable in slots 25a in a manner similar to the operation of detents36 in Fig. 5. Detents 2611 are movable in slots 25g in a manner similarto the operation of detents 26' in Fig. 6. A bore 8a is formed in thebody portion 1 and has seated therein a retainer ring 42 for holding thedetents assembled in their slots and also to form a surface upon whichthe pointed ends 28a of the detents 36a will pivot. The ends 28b of'thedetents 26a will pivot on the front face 29a of the body portion 1, asclearly shown in Fig. 8. Fingers 27a of detents 26a and 36a bear againstthe abutment 24a for retracting the firing pin and spring to armedposition.

The operation of the device shown in Figs. 7 and 8 is I as follows:

In flight the detents 26a and 36a move outwardly in response tocentrifugal force. During this movement the fingers 27a of the detents36a pivot away from the abutment 24a while the fingers27a on the detents26;: remain in contact with the abutment and hold the spring 22acompressed and the firing pin 7a in armed position. On impact with atarget the nose cap and insert are deformed and the firing pin isprojected into the primer 5. 'In the event that the detents do not yieldto the force of impact the separable member 41 will release itself fromthe annular grooves 40 and let the firing pin slide through to strikethe primer 5.

While we have disclosed three forms of the present invention presentlypreferred by us, various changes and modifications will occur to thoseskilled in the art after a study of the present disclosure. Hence thedisclosure is to be taken in anillustrative rather than a limitingsense; and it is our desire and intention to reserve all modL ficationsfalling within the scope of the subjoined claims.

Having now fully disclosed the invention, what we claim and desire tosecure by Letters Patent is:

1. In an impact detonated fuze having a body portion, a nose cap securedon the front end thereof and having an insert therein, a cylindricalguide member in said nose cap having an annular spring seat, acentrifugally operated rotor having an ignition charge and a recesstherein and being movable from a safe to an armed position, an axiallydisposed firing pin having its rear end engaged in the recess and havingan enlargement thereon forming a shoulder, an elongated sleevesurrounding said firing pin and slidable thereon, an annular abutment onthe rear end of said sleeve normally engaging the firing pin shoulder, aspring surrounding said sleeve and firing pin and being confined betweensaid abutment and annular spring seat normally urging said firing pininto the recess, and a centrifugally operated detent in engagement withsaid annular abutment and pivotable on the body under the influence ofspin for retracting said sleeve and abutment, compressing said spring,and releasing said firing pin to float freely in said sleeve and creepforward to armed position on forward acceleration said detent beingoperable on decay of spin to release said annular abutment to the biasof said spring whereby said firing pin is urged into the primer.

2. in an impact detonated fuze having a body portion, a nose cap securedon the front end thereof, an insert in said nose cap having a series ofslots diametrically disposed and circumferentially spaced, atcentrifugally operated rotor having an ignition charge and a recesstherein and being movable from a safe to an armed position, an axiallydisposed firing pin having its rear end engaged in the recess and havingan enlargement thereon forming a shoulder, an elongated sleevesurrounding said firing pin and slidable thereon, an annular abutment onthe rear end of said sleeve normally engaging the firing pin shoulder, aspring surrounding said sleeve and firing pin and being confined betweensaid abutment and nose cap normally urging said firing pin into therecess, a first pair of diametrically opposite centrifugally operateddetents confined for opposite radial movement in the diametricallyopposite slots in said insert and in engagement with said annularabutment and pivotable on the body under the influence of spin forretracting said sleeve and abutment, compressing said spring, andreleasing said firing pin to float freely in said sleeve and creepforward to armed position, and a second pair of dimetrically oppositecentrifugally operated detents confined in diametrically opposite slotsin said insert and in engagement with said annular abutment andpivotable on the body under the influence of spin for assisting saidfirst pair of detents during initial retraction of said abutment andspring and later releasing said abutment and spring to be held by saidfirst pair of detents.

3. A centrifugally armed impact detonated fuze having a body, aspherical rotor mounted for universal rotation within said body, aprimer charge axially disposed within said rotor, a recess on theperiphery of said rotor, an axially disposed firing pin having its rearend in engagement with said recess in unarmed position for holding saidcharge at an angle to said firing pin, said firing pin having an annularabutment member mounted thereon, spring means mounted in said body torestrain said firing pin in said recess to maintain said rotor in theunarmed position, and a plurality of centrifugally operated detentsabutting said body in unarmed position and initially pivotable inresponse to spin of said body to urge said abutment member forwardagainst the action of said spring means to efiect removal of said firingpin from said recess and releasing said rotor for precession to therebyalign said charge with said firing pin, at least one of said detentsbeing so shaped as to move clear of and release said abutment uponextended pivoting.

4. A centrifugally armed impact detonated fuze as set forth in claim 3wherein said firing pin has a beveled annular recess therein, saidannular abutment member mounted on said firing pin in engagement withsaid recess and releasable therefrom upon impact with said target.

5. A centrifugally armed impact detonated fuze having a body, aspherical rotor mounted for universal rotation Within said body, aprimer charge axially disposed Within said rotor, a recess on theperiphery of said rotor angularly disposed relative to said charge, aninsert secured to the front end of said body, a firing pin axiallydisposed within said insert having its rear end in engagement with saidrecess in unarmed position to hold said charge at an angle to saidfiring pin, said firing pin having an annular abutment member mountedthereon, a spring surrounding said firing pin and engaging said abutmentmember to restrain said firing pin in said recess, said insert having aplurality of radially disposed guide slots, a series of centrifugallyoperated detents in engagement with said abutment member, said detentshaving a width slightly less than the widthof said guide slots andpivotable on the body within respective guide slots in response to spinof said body to urge said abutment member forward against the action ofsaid spring to eifect removal of said firing pin from said recessreleasing said rotor for precession to thereby align said charge withsaid firing pin at least one of said detents being so shaped as to moveclear of and release said abutment upon extended pivoting.

References Cited in the file of this patent UNITED STATES PATENTS2,014,393 Mathsen Sept. 17, 1935 2,564,797 Thompson Aug. 21, 19512,626,568 Podnos Jan. 27, 1953 2,641,186 Apotheloz June 9, 1953 FOREIGNPATENTS 505,338 Great Britain May 9, 1939 580,243 Great Britain Sept. 2,1946 928.644 France June 9, 1947 138.839 Sweden Jan. 20, 1953 1,063,268France Dec. 16, 1953

